The present invention relates to flow measuring method suitable for measurement of flow within an open tube having a very small diameter, which may be provided for a separation analysis field such as liquid chromatography and electrochromatography, a chemosynthesis field, and the like.
Conventionally, the flow within an open tube having a very small diameter is measured by methods such as: a first method of calculating volume of a discharge portion of a pumping device; a second method of attaching a fan to a passage and calculating the flow from the revolution of the fan; a third method of inserting two filaments, heating one of them, and calculating the flow from speed of conduction of heat to the other filament; and a fourth method of intermittently passing a substance different from a fluid, such as bubbles, into a passage and converting pass time into flow by using an optical sensor.
However, in the conventional methods of measuring flow within an open tube, the first and second methods have a problem such that a mechanical error may occur in a measurement value. The third method has a problem that the filaments are worn out and cut. The fourth method has problems such that, since a foreign matter is inserted into a passage, it is difficult to insert the foreign matter and that the passage is contaminated due to the insertion of the foreign matter. Consequently, any of the methods is not suitable for the separation analysis field, chemosynthesis field, and the like.
An object of the present invention is therefore to provide a method for measuring flow within an open tube, in which a mechanical error and contamination of a passage do not occur, as a method for measuring flow within an open tube having a very small diameter provided for the separation analysis field and chemosynthesis field.
To achieve the above-mentioned object, according to a method for measuring flow within an open tube of the present invention, a change in physical properties of a fluid within an open tube which is caused by heating an arbitrary portion in the open tube by heating means is detected by using a detector disposed with a predetermined spacing from the heating portion, thereby measuring the flow in the open tube.
Further, according to a method for measuring flow within an open tube of the present invention, a change in physical properties of a fluid within an open tube which is caused by heating an arbitrary portion in the open tube by heating means is detected by using a detector disposed with a predetermined spacing from the heating portion, thereby measuring the flow within the tube and, further, the flow is computing-processed by a computer system to thereby obtain a flow signal.
According to a method for measuring flow within an open tube of the present invention, a time difference between time at which heating is started by the heating means and time at which a signal is detected by the detector is measured.
The heating means used for the measuring method of the present invention may be current-passing heating means or light-condensing heating means. The heating by the heating means may be performed by a gradient voltage.
The open tube used for the measuring method of the present invention may be a capillary column for use in capillary electrophoresis, capillary liquid chromatography, and the like, a pre-column or a post column for use in gas chromatography, liquid chromatography, and the like, a catheter or a tube connected to a catheter for use in a system for automatically supplying chemical to an animal or a human being, a micropipet or a tube connected to a micropipet for use in study of life science, and the like.
A change in physical properties of the fluid within the tube in the measuring method of the present invention may be a change in temperature or occurrence of bubbles.
Further, a detector for use in the measuring method of the present invention may be constructed by a combination of an infrared LED and a photodiode.
The above and other objects and effects of the present invention will become apparent in the following description with reference to the accompanying drawings.